JP2003279974A - Image display device using microlens array and image projection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device in which the convergence efficiency of light to the respective pixels of a space light modulation element is excellent and which is simply structured and easily manufactured at a low cost. <P>SOLUTION: A lens array in first and second microlens arrays corresponds to a pixel array in the space light modulation element 4, the first and second microlens arrays 1 and 3 are made to face each other across a prescribed clearance 2, and the space light modulation element 4 is arranged near or in close contact with the first microlens array 1. The light made incident from the side of the second microlens array 3 is converged to the respective pixels of the space light modulation element 4 by the respective microlenses of the first and second microlens arrays 1 and 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device and an image projection device using a microlens array.

[0002]

2. Description of the Related Art Projectors for displaying video images, computer output images, and the like have become widespread. 2. Description of the Related Art Recently, development of projectors has been advanced with the aim of achieving high definition of images, high illuminance, downsizing of devices, and cost reduction.

Although the pixel size on the light valve has been reduced in order to improve the definition of the image, the area occupied by wirings other than the pixel (black matrix) has been accompanied by the reduction in the pixel size. Is relatively large, the aperture ratio is lowered, the projected image is darkened, and the image quality is deteriorated.

To solve this problem, it has been proposed to arrange a microlens corresponding to each pixel on the light valve and improve the aperture ratio by utilizing light collection by the microlens (Japanese Patent No. 3110652). Publication, Japanese Patent Laid-Open No. 200
0-19307, etc.). In this case, it is important that the incident light is efficiently condensed by the microlens on the pixel of the light valve, and that the microlens array and the spatial light modulator are integrated to facilitate manufacturing.

In the image display device described in each of the above publications, a "single microlens array" is used, and light is condensed on each pixel by a single microlens surface. If the radius of curvature of the microlens is decreased as much as possible, the spherical aberration is deteriorated and the noise component to the adjacent pixel is increased. If the radius of curvature is increased, the light-collecting power is weakened and the effect of improving the aperture efficiency cannot be sufficiently obtained. There is a problem.

As a method for solving such a problem,
Japanese Unexamined Patent Application Publication No. 2000-305472 discloses an arrangement in which two microlens arrays are used to efficiently collect light on each pixel.

However, the image display device described in this publication is "from the side on which light is incident, the transparent substrate, the second microlens, the second adhesive, the second cover glass, the gel adhesive, and the first micro. The lens, the first adhesive, and the first cover glass are provided, and the first cover glass and the light valve are integrated with each other. "Since the whole has a multi-layer structure, the number of members used and the number of manufacturing steps are increased. However, it is hard to say that the production is not always easy and the cost is sufficiently low.

[0008]

SUMMARY OF THE INVENTION According to the present invention, two microlens arrays and a spatial light modulator are combined, and the efficiency of collecting light on each pixel of the spatial light modulator is good.
Another object is to provide a novel image display device that has a simple structure, is easy to manufacture, and can be realized at low cost.

Another object of the present invention is to provide a novel image projection device using the above image display device.

[0010]

An image display device according to the present invention comprises a spatial light modulator, a first microlens array,
It has a second microlens array. The "spatial light modulator" spatially modulates the intensity of transmitted light or reflected light.
As the spatial light modulator, a transmissive or reflective liquid crystal light valve that has been widely known in the related art can be used.

In the "first microlens array and the second microlens array", the lens array of the microlenses in each corresponds to the pixel array in the spatial light modulator. Here, "corresponding to the lens array of the microlens and the pixel array placed in the spatial light modulator" means
By adjusting the position of the microlens array with respect to the spatial light modulator, it means that the array of the microlens array can be overlapped with the pixel array.

The first and second microlens arrays are opposed to each other with a "predetermined gap" therebetween, and the first microlens array is provided on the side opposite to the second microlens array through the first microlens array. Spatial light modulators are arranged close to or close to each other. That is, the spatial light modulator, the first microlens array, and the second microlens array are arranged in this order.

The light to be incident on the spatial light modulator is incident from the second microlens array side and is condensed on each pixel of the spatial light modulator by each microlens of the first and second microlens arrays. It

In this way, since the incident light is condensed on the pixel by each microlens of the two microlens arrays, the condensing power of each microlens can be set reasonably to "not worsen the spherical aberration". it can.

As described above, since the first and second microlens arrays are opposed to each other with a predetermined gap therebetween,
There is a "predetermined gap" between them. The portion of the predetermined gap may be an air layer, but may be "filled with resin" (claim 2). Thus, when the space between the first and second microlens arrays is filled with resin, the radius of curvature or the focal length of the microlenses can be adjusted by adjusting the relationship between the filling resin and the refractive index of each microlens array material. Therefore, the degree of freedom in designing the refractive power of each microlens is increased, and the manufacture of each microlens array is facilitated.

In the first and second microlens arrays of the image display device according to the first or second aspect, the lens arrays of the microlenses of each microlens array are "overlapped with the pixel array of the spatial light modulator". However, the microlens array pitch in the first and second microlens arrays can be shifted by a half pitch in at least one direction (claim 3). in this case,
The lens arrangement of one microlens array overlaps with the pixel arrangement, but the lens arrangement of the other microlens array is shifted by a half pitch in at least one of the vertical and horizontal directions of the lens arrangement.

In the image display device according to the third aspect of the invention, the microlenses of the first microlens array can have a convex shape and the microlenses of the second microlens array can have a concave shape (claim 4). Alternatively, the microlenses of the first microlens array may be concave and the microlenses of the second microlens array may be convex (claim 5).

At least one of the first and second microlens arrays in the image display device according to any one of claims 3 to 5 can have a "structure having a gap between the microlenses" (claim). Item 6), and at least one of the first and second microlens arrays in the image display device according to any one of claims 3 to 6 may have a “structure in which microlenses are densely arranged” ( Claim 7).

The image display device according to any one of claims 1 to 7 may have a spacer for maintaining and / or adjusting the gap and / or the position between the first and second microlens arrays. (Claim 8).

The image projecting apparatus of the present invention comprises:
The image display device according to any one of 1., a light source, and a projection lens (claim 9).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described below. FIG. 1 (a) schematically illustrates one embodiment of the image display device. Reference numeral 1 is a first microlens array, reference numeral 3 is a second microlens array, and reference numeral 4 is a spatial light modulator.

In this embodiment, the spatial light modulator 4 is a reflective "liquid crystal light valve" and spatially modulates the intensity of the reflected light. The first microlens 1 and the second microlens array 3 are formed with microlenses arranged at the same pitch as the pixel arrangement in the spatial light modulation element 4, and from the direction 200 perpendicular to the pixel surface of the spatial light modulation element 4. As seen, both the first and second microlens arrays have a positional relationship such that the array of each microlens overlaps the pixel array.

The first and second microlens arrays 1 and 3 are separated from each other by a predetermined gap 2, and the microlenses are opposed to each other.
On the opposite side of the microlens array 3, the spatial light modulation element 4 is arranged in close contact with the first microlens array 1. The gap 2 is an “air layer”. And the whole is integrated by an appropriate means.

Light 5 to be incident on the spatial light modulator 4
Enters from the second microlens array 3 side,
The light is focused on each pixel of the spatial light modulator 4 by each microlens of the second microlens arrays 1 and 3.

In FIG. 1B, reference numeral PC indicates one of the pixels in the spatial light modulator 4, and reference numeral 6 indicates a light spot condensed on the pixel PC. At this time, when the size of the light spot 6 condensed on the pixel PC is “smaller than the pixel size”, the spot image smaller than the pixel on the screen is reflected on the pixel PC and emitted. The projected image is a “high-definition image”.

The spatial light modulator in the image display device shown above is a reflective liquid crystal light valve as described above. As such a liquid crystal light valve, LCOS
(LiquidCrystal on Si) is known. Of course, a "transmissive liquid crystal light valve" can be used as the spatial light modulator.

That is, the image display device shown in FIG. 1 includes the spatial light modulator 4 for spatially modulating the intensity of the reflected light, and the first and second spatial light modulators.
A microlens array 1 and 3, and a first and a second
The lens array in the microlens arrays 1 and 3 corresponds to the pixel array in the spatial light modulation element 4, and the first and second microlens arrays 1 and 3 are opposed to each other with a predetermined gap 2 therebetween to form the first microlens. Second through array 1
The spatial light modulator 4 is disposed on the side opposite to the microlens array 3 so as to be in close contact with the first microlens array 1.
A structure in which light incident from the second microlens array 3 side is condensed on each pixel of the spatial light modulator 4 by each microlens of the first and second microlens arrays 1 and 3 (claim 1).

The materials of the first and second microlens arrays 1 and 3 can be minerals, resins, etc., but glass is generally used. Considering the dry etching process for forming the microlens array, “alkali-free or low-alkali glass” is preferable. Quartz glass (n (refractive index, the same applies hereinafter) = 1.46) can be mentioned as a typical example.

When the gap 2 is filled with resin, as described above,
By adjusting the relationship between the refractive index of the filling resin and the refractive index of the material of the microlens arrays 1 and 3, it is possible to adjust the radius of curvature and the focal length of the microlenses, and to design the refractive power of each microlens. This increases the degree of freedom in manufacturing each microlens array.

In such a case, as the quartz glass as the microlens array material, the difference in the refractive index and the linear expansion coefficient between the resin and the microlens array material (if the thermal expansion coefficient is largely different, the heating process is performed during the manufacturing process). If it contains, there is a problem that the microlens array and the resin may peel off due to heat stress.) Considering cost reduction,
1737 (n = 1.52) manufactured by Corning Co., Neoceram N-0 (n = 1.541) manufactured by Nippon Electric Glass Co., Ltd. are preferable.

A UV-curable resin is suitable as the resin to be filled in the gap between the first and second microlens arrays, and is acrylic and has a refractive index of 1.40 to 1.70 (for example, manufactured by NTT Advanced Technology). Are known, and these can be appropriately selected and used.

When manufacturing a microlens array, a glass substrate having a thickness of about 1 mm is often used. Even after the lens is formed by dry etching, the thickness is about this. Such a microlens array is commercially available (for example, manufactured by MEMSOPTICAL, pitch 15 μm to 500 μm, lens shape, circle, square, etc., substrate: quartz glass).

The thickness of 1 mm is to secure the strength of the substrate, but it is possible to reduce the thickness to several tens of μm by polishing, and it goes without saying that a thin microlens array can be manufactured.

As shown in FIG. 1, "first and second with a gap 2 in between.
The configuration in which the microlens arrays 1 and 3 are arranged, and the spatial light modulator 4 is brought into close contact with the first microlens 1 to integrate the whole "is simple and has a small number of members, so that the number of manufacturing steps is small, which is easy and inexpensive. Can be manufactured. Further, since the two microlens arrays are used, the light collection efficiency of each microlens can be set without difficulty, the incident light can be efficiently collected on the pixel, and the noise light to the adjacent pixel can be reduced. .

When the light is condensed by the microlens array, a light intensity distribution is generated on each pixel, and the profile is two-dimensionally viewed, and the profile is as shown in FIG. If the skirt of this profile is within one pixel, there is no noise light to adjacent pixels. Also, the more thin the profile is, the more highly projected the image is projected.

The half value width: HV of the profile of the light intensity distribution is used as an index of the high definition image. Full width at half maximum of profile: The smaller the HV, the higher the definition. On the other hand, light utilization efficiency is also important as performance. The “light utilization efficiency” is determined by how the light passing through one microlens is condensed on the corresponding one pixel without loss.

The profile shown in FIG. 8 "has a slight skirt extending to adjacent pixels", resulting in a slight loss of light utilization efficiency. This lost light component is "noise light" when viewed from adjacent pixels.
This causes deterioration of the image quality of the projected image.

Numerical examples are shown below. Comparative numerical examples 1 and 2 given at the beginning are examples when one microlens array is used. That is, the microlens array is arranged so that the “microlenses are on the pixel side” in the vicinity of the pixel surface of the spatial light modulator, the microlens array is overlapped with the pixel array, and the gap between the two is made of transparent resin. It is a filled structure.

Comparative Numerical Example 1 Pixel size: 14 μm square (refers to a square shape with one side of 14 μm. The same applies hereinafter) Refractive index of resin filled in the gap: 1.4 Microlens array Refractive index: 1.52 Microlens (convex ) Radius of curvature:
7 μm Distance from microlens tip to pixel (gap filled with resin): 30 μm Half-width of profile of light intensity distribution of light focused on pixel: 5.1 μm Light utilization efficiency: 65% In case of this comparative numerical example 1 , The radius of curvature of each microlens in the microlens array is as small as 7 μm,
Incident light is highly condensed. The half-width of the profile is 5.1
The micro-lens is small and the profile is sharp, but the spherical aberration of the microlens is large, there is a lot of "noise light" going to the adjacent pixel direction, the light loss is large, and the light utilization efficiency is 65.
% Is low.

Numerical comparison example 2 Pixel size: 14 μm square Refractive index of resin filled in gap: 1.4 Microlens array refractive index: 1.52 Microlens (convex) radius of curvature:
10 μm Distance from tip of microlens to pixel (gap filled with resin): 30 μm Half-value width of profile of light intensity distribution of light focused on pixel: 8.6 μm Light utilization efficiency: 95% Microlens in Comparative Numerical Example 2 Has a large radius of curvature,
Since the spherical aberration is small, the light is condensed on the pixel, the loss of the light is small, and the light utilization efficiency is high. The full width at half maximum of the profile is large and the profile is broad. However, even though the full width at half maximum is large, it is 61% compared to the size of the pixel, and in comparison with Comparative Numerical Example 1 in terms of high definition of the projected image. Although slightly inferior, if the light utilization efficiency is the same and the half width is less than this, it can be said that the configuration is excellent.

[0041]

EXAMPLES Specific examples of the above-described embodiments will be given below. Example 1 Pixel size: 14 μm square Gap between microlenses: Air layer (refractive index: 1) First microlens array refractive index 1.52 Microlens (convex) radius of curvature: 1
0 μm Thickness of the first microlens array (distance from the tip of the microlens to the surface of the spatial light modulator close to the first microlens array. The same applies to each of the following embodiments): 30 μm Second microlens Array refractive index 1.52 Micro lens (convex) radius of curvature: 2
0 μm Gap between microlens arrays (from lens tip to tip): 3 μm Full width at half maximum of profile: 7.6 μm Light utilization efficiency: 100% Example 2 Example 2 has a refractive index of 1.4 in the gap between the microlenses. It is an example when filling the member of. In this example, it can be seen that the full width at half maximum is even smaller than when the gap is an air layer.

Pixel size: 14 μm Refractive index of resin filled in gaps between microlenses: 1.
4 First microlens array refractive index 1.52 Microlens (convex) radius of curvature 2
0 μm First microlens array thickness: 30 μm Second microlens array refractive index: 1.52 Microlens (convex) radius of curvature:
10 μm Gap between microlens arrays (from the tip of the lens to the tip): 3 μm Full width at half maximum of profile: 6.2 μm Light utilization efficiency: 97% In both Examples 1 and 2, Comparative Numerical Examples 1 and 2 were compared. The half-width of the profile is narrow and the light utilization efficiency is high. That is, in Examples 1 and 2, a high-definition and bright projection image can be realized.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 schematically shows another embodiment of the image display device. As shown in FIG. 2A, this image display device has a spatial light modulator 4a that spatially modulates the intensity of transmitted light or reflected light, and first and second microlens arrays 1a and 3a. The lens arrangement in the first and second microlens arrays corresponds to the pixel arrangement in the spatial light modulator 4a, and the first and second
The microlens arrays 1a and 3a are opposed to each other with a predetermined gap 2a between them, and the first microlens array 1a is provided on the side opposite to the second microlens array 3a, in close contact with the first microlens array 1a, A light modulation element 4a is arranged so that light incident from the second microlens array 3a side is condensed by each microlens of the first and second microlens arrays to each pixel of the spatial light modulation element 4a. (Claim 1). The whole is integrated by appropriate means.

The array of microlenses in the first microlens array 1a overlaps with the pixel array in the spatial light modulator 4a when viewed from the optical axis direction, but the array pitch of the microlenses of the second microlens 3a. Is shifted in one direction (left and right direction in the figure) by a half pitch with respect to the arrangement pitch of the microlenses in the first microlens array 1a, but may be shifted in the direction orthogonal to the drawing.

In this way, the incident light is first condensed by the second microlens array 3a and then condensed by the first microlens array 1a through the gap 2a (in a region within 1/2 of each microlens). To be done. When the radius of curvature of the microlenses of the second microlens array 3a is small and is close to a hemispherical shape, spherical aberration is large, and conversely, when the radius of curvature is large, there is a problem that the light bending force is weak and light cannot be efficiently condensed. This tendency becomes remarkable especially around the lens.

When the second microlens array 3a is displaced from the first microlens 1a, the arrangement is as shown in FIG.
As shown in, the light 5a that has passed through the lens periphery of the microlens L3a of the second microlens array will pass through the vicinity of the center of the microlens L1a in the first microlens array 1a, so that it is efficiently condensed on the pixel. it can. Further, for example, when the radius of curvature of the microlenses L3a of the second microlens array is small with respect to the pixel size and gaps are formed at the four corners of the pixel in the diagonal direction, the light passing through these four corners travels substantially straight, and tentatively. If the first and second microlens arrays do not have the above “deviation”, they are not focused on the pixel center.

However, the second microlens array 3a
2 is displaced from the first microlens array 1a as shown in FIG. 2, the "substantially straight light" passes through the microlenses of the first microlens 1a and is effectively condensed on the pixel.

Further, when a light-shielding layer (black matrix) is provided in an actual liquid crystal light valve, the above-mentioned light that travels substantially straight is shielded by the light-shielding layer, which does not lead to deterioration of the image but reduces the light utilization efficiency. .

Although the case where the microlenses in the first and second microlens arrays have a convex shape is shown above, when the resin is filled in the gap between the first and second microlens arrays, the refraction of the resin is performed. The shape of the microlenses in each microlens array may be a convex shape depending on the size relationship of the index: n2, the refractive index of the material of the first microlens array: n1, and the refractive index of the material of the second microlens array: n3. It is also possible to have a concave shape.

That is, when both the lens shapes of the first and second microlens arrays are convex, n3> n1
> N2, n1 = n3> n2 or n1>n3> n2 is satisfied, and conversely, when both are concave surfaces, n1 <n3 <n2, n1 = n3 <n2, or n
It suffices if 3 <n1 <n2 is satisfied. In this case, each microlens functions as a positive lens.

FIG. 3 shows another embodiment of the image display device as an explanatory view. As shown in FIG. 3A, in this embodiment, the microlenses of the first microlens array 1b provided in close contact with the spatial light modulator 4b are concave and the microlenses of the second microlens array 3b are microscopic. The lens has a convex shape (claim 5). The whole is integrated by appropriate means.

The array of microlenses in the first microlens array 1b overlaps the pixel array in the spatial light modulator 4b, but the array pitch of the microlenses of the second microlens 3b is the first.
The microlens array 1b is deviated from the array pitch of the microlenses by a half pitch in two directions (a horizontal direction in the drawing and a direction orthogonal to the drawing) (claim 3).

As shown in FIG. 3B, the light 5b collected by the microlens L3b of the second microlens array
However, the light enters the periphery of the first microlens array 1b and is efficiently condensed toward the pixel by the negative power of the microlens L1b.

Contrary to the example of FIG. 3, even if the microlenses of the first microlens array are convex and the microlenses of the second microlens array are concave (claim 4), the incident light is directed to the pixels. It can collect light efficiently.

[0055]

EXAMPLES Examples of the image display device according to claim 5 will be described below. Example 3 Pixel size: 14 μm square Refractive index of resin filled in gaps between microlens arrays: 1.4 First microlens array refractive index: 1.52 Microlens (concave) radius of curvature:
25 μm Thickness of first microlens array: 30 μm Refractive index of second microlens array: 1.52 Radius of curvature of microlenses (convex):
25 μm Microlens array spacing (from the center of the microlenses of the second microlens array to the ends of the microlenses of the first microlens array): 3 μm Full width at half maximum of profile: 6.2 μm Light utilization efficiency: 90% Also in Example 3 Since the "half-width of profile" is narrow and the light utilization efficiency is high, a high-definition and bright projection image can be realized.

FIG. 4 is an explanatory view showing another embodiment of the image display device.

In FIG. 4A, the spatial light modulator 4e.
On the microlens formation surface of the first microlens array 1e provided in close contact with the microlens array 1e, there is a gap portion 10 between the arranged microlenses 1e1 (claim 6), and this gap portion 10 is a "flat surface". is there. Spatial light modulator 4
When the pixel size (pixel pitch) in e is “d”, the radius of curvature r of the microlenses of the first microlens array 1e is smaller than the above d (for square pixels, for example, r <( d / 2)). The microlens 1e1 has a concave shape. The whole is integrated by appropriate means.

The array pitch of the microlenses of the first microlens array 1e and the second microlens array 3e is set in the horizontal direction of the drawing and in the direction orthogonal to the drawing.
They are offset from each other by ½ pitch (claim 3). The microlens 3e1 formed in the microlens array 3e has a convex shape.

The square lattice shown in FIG. 4 (b) is
The arrangement | positioning of the micro lens 3e1 in the state which saw the 2nd micro lens array 3e from the optical axis direction is shown. That is, each grid in the grid is a microlens 3e1. In other words, the individual microlenses 3e1 have “square lens edge portions” when viewed from the optical axis direction, and these edge portions are adjacent to each other. That is, in the second microlens array 3e, the arrangement of the microlenses 3e1 is "dense" (claim 7).

In FIG. 4B, the microlens 3e
The microlenses 1 of the first microlens array 1e are arranged at the respective lattice points of the lattice showing the lens edges in the arrangement of 1.
e1 is located. The center of each microlens 3e1 corresponds to the center of each pixel in the spatial light modulator 4e.

Of the light 5 condensed by the microlenses 3e1 of the second microlens array, the light 5b passing near the lens center of the microlenses 3e1, that is, near the optical axis.
Is not affected by the aberration of the microlens 3e1 so much, it is not necessary to further focus this light 5b by the microlens of the first microlens array, and the light 5b passes through the lens periphery of each microlens 3e1 of the second microlens array. Only the light 5c which has
Due to the negative power of the concave microlens 1e1, the light is focused on the optical axis side of the microlens 3e1.

An example relating to this embodiment will be given.

[0063]

Example 4 Pixel size: 14 μm square Refractive index of resin filled in gap between microlens arrays: 1.4 First microlens array refractive index: 1.52 Microlens (concave) radius of curvature:
25 μm Thickness of first microlens array: 30 μm Refractive index of second microlens array: 1.52 Radius of curvature of microlenses (convex):
25 μm Microlens array spacing (from center of microlens of second microlens array to flat portion of first microlens array): 2.4 μm Length of flat portion between adjacent microlenses in first microlens array (Fig. Edge separation of the microlenses 1e1 in the vertical and horizontal directions in 4 (b)): 4 μm Full width at half maximum of profile: 4.7 μm Light utilization efficiency: 97% Full width at half maximum of profile is very small, high light utilization efficiency and high definition A bright projected image can be realized.

FIG. 5 shows a modification of the embodiment shown in FIG. In this example, each microlens array 3e1 of the second microlens array is a "square lens edge" when viewed from the optical axis direction, as in the example of FIG.
And are adjacent at these edges. That is, the arrangement of the microlenses 3e1 in the second microlens array 3e is "dense" (claim 7).

On the side of the first microlens array, as in the example of FIG. 4, the microlenses 1e1 having a concave shape are "each lattice point of the lattice indicating the lens edge portion in the array of the microlenses 3e1". In addition to this, in addition to this, the convex microlens 1e is located so as to be positioned at each central portion of the grating when viewed from the optical axis direction.
2 are arranged. That is, the array of microlenses 1e2 having positive power overlaps the array of microlenses 3e1 and also the array of pixels.

The curvature radii r1 of the microlenses 1e1 and 1e2 of the first microlens array are smaller than the pixel size d (for example, r1 <(d / 2)), and the microlenses 3e1 of the second microlens array are curvature radius:
r2 is larger than the pixel size (for example, r2> d√
(2)) (for square-shaped pixels).

Of the light collected by each microlens 3e1 of the second microlens array, the light passing through the lens peripheral portion is collected toward the pixel center by the negative power of the microlens 1e1. Also, the micro lens 3
The light passing through the center of e1 is further condensed toward the center of the pixel by the microlens 1e2.

That is, as compared with the case of FIG. 4, not only the light passing through the periphery of the microlens 3e1 but also the light passing through the center of the lens can be effectively focused toward the pixel center, so that the light can be efficiently reflected on the pixel. You can collect.

That is, the embodiment of FIG. 5 has the first microlens array and the second microlens array, and the arrangement of the microlenses 1e1 and 1e2 in the first microlens array and the microlenses in the second microlens array. The array of the lenses 3e1 corresponds to the pixel array. The array of microlenses 1e2 and 3e1 corresponds to overlap the pixel array, and
The arrangement corresponds to the pixel arrangement with a 1/2 pitch shift in the vertical and horizontal directions.

FIG. 6 is an explanatory view showing an embodiment of an image display device according to claim 8. Spatial light modulator 4b
The first microlens array 1b 'is provided in close contact with the second microlens array 3b with a gap 2b' interposed therebetween.
b'is provided and is wholly integrated. First microlens array 1b ', second microlens array 3
“Columnar” spacers 101 and 102 are formed outside the area of the microlens forming surface of b ′.

The spacers 101 and 102 are for maintaining the gap 2b ′ between the first and second microlens arrays, and the first and second microlens arrays 1b ′ and 3 are provided.
When the microlens b'is formed by dry etching, the spacers 101 and 102 are formed so that the distance between them is the same, and they are aligned after manufacturing.

By doing so, not only can the gap between the first and second microlens arrays be made constant, but also the alignment of the microlenses between the microlens arrays in a plane (matching their pitches, It is also easy to shift by 1/2 pitch as shown in the figure. That is, when the pitches of the microlens arrays are shifted from each other as shown in the figure, the spacers 101, 10 are placed at positions shifted by 1/2 pitch.
2 is prepared in advance.

A technique for producing a columnar spacer at the same time as the microlens array is disclosed in Japanese Patent Laid-Open No. 2000-19307, and this method may be used.

FIG. 7 is an explanatory view showing one embodiment of the image projection apparatus. Reference numeral 9 is a “light source”, reference numeral 10 is a “polarization beam splitter”, reference numeral 11 is an “image display device”,
Reference numeral 12 is a "projection lens" and reference numeral 13 is a "screen"
Is shown.

From the light source 9, an S-polarized light beam is incident on the polarization beam splitter 10, enters the polarization beam splitter 10, is reflected by the polarization beam splitter 10, and enters the image display device 11. Image display device
As described with reference to FIG. 6, the first and second microlens arrays are arranged close to each other with a gap, and the spatial light modulator is arranged closely to the first microlens array. The element is a reflective liquid crystal light valve.

When the liquid crystal light valve is driven by the image signal, the reflected light beam in the pixel corresponding to the image to be displayed is converted into the P polarization state by the polarization beam splitter.
This light beam passes through the polarization beam splitter 10, and is imaged and displayed as a projection image on the screen 13 by the projection lens 12.

In the spatial light modulator, the pixel array 14 is a dense array as shown in FIG. 7B, but the incident light becomes a spot smaller than the pixel size on each pixel due to the microlens array. An image obtained by projecting this spot by the projection lens 12 becomes an image 15 with a gap as shown in FIG. 7 (c). That is, the image 15 is a high definition image. A white lamp such as a halogen lamp or an ultra-high pressure mercury lamp is mainly used as a light source, but a laser or an LED may be used.

In the pixel projection device of FIG. 7, when the image display device 11 is oscillatingly displaced at a high speed in a plane orthogonal to the optical axis of the projection lens 12 by using a piezoelectric element or the like, the projected high definition image is obtained. Since the image 15 is finely displaced at a high speed and the gaps between the pixel images are filled, a good high-definition image in which the gaps are not noticeable can be realized.

[0079]

As described above, according to the present invention, a novel image display device and a novel image projection device using the same can be realized. As described above, the image display device of the present invention uses two microlens arrays to focus the incident light flux on each pixel of the spatial light modulator, so that the power of the microlenses of each microlens array is set without difficulty. As a result, light can be efficiently condensed on each pixel, and the light utilization efficiency is high, so that a high-definition and bright projection image can be realized. Moreover, since the image display device has a simple structure, it can be easily and inexpensively manufactured.

Therefore, the image projection apparatus using this image display apparatus can display a bright, high-definition and excellent image.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of an image display device.

FIG. 2 is a diagram for explaining an embodiment of an image display device.

FIG. 3 is a diagram for explaining an embodiment of an image display device.

FIG. 4 is a diagram for explaining an embodiment of an image display device.

FIG. 5 is a diagram for explaining a modification of the embodiment of FIG.

FIG. 6 is a diagram illustrating an image display device using a microlens array having spacers formed therein.

FIG. 7 is a diagram for explaining the embodiment of the image projection apparatus.

FIG. 8 is a diagram for explaining the light condensing property of a microlens.

[Explanation of symbols]

1 First microlens array 2 gap 3 Second microlens array 4 Spatial light modulator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuyuki Takiguchi             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh (72) Inventor Kazuya Miyagaki             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh (72) Inventor Kenji Kameyama             1-3-3 Nakamagome, Ota-ku, Tokyo, stock             Company Ricoh F term (reference) 2H088 EA37 EA44 HA20 HA25 MA06                 2H091 FA10Z FA26X FA26Z FA29X                       FA29Z FA35Y FA41Z LA16                       MA07

Claims (9)

[Claims] 1. A spatial light modulator for spatially modulating the intensity of transmitted light or reflected light, and first and second microlens arrays, wherein the lens arrangement in the first and second microlens arrays is the spatial light. Corresponding to the pixel array in the modulator, the first and second microlens arrays are opposed to each other with a predetermined gap therebetween, and the first and second microlens arrays are arranged on the opposite side of the second microlens array. First above
The spatial light modulator is arranged close to or in close contact with the microlens array, and light incident from the second microlens array side is converted into the space by the microlenses of the first and second microlens arrays. An image display device characterized in that it is configured to collect light on each pixel of a light modulation element. 2. The image display device according to claim 1, wherein a resin is filled between the first and second microlens arrays. 3. The image display device according to claim 1 or 2, wherein the microlens array pitches in the first and second microlens arrays are shifted by at least one direction in a half pitch. 4. The image display device according to claim 3, wherein the microlenses of the first microlens array are convex and the microlenses of the second microlens array are concave. 5. The image display device according to claim 3, wherein the microlenses of the first microlens array are concave and the microlenses of the second microlens array are convex. 6. The image display device according to any one of claims 3 to 5, wherein at least one of the first and second microlens arrays has a gap between the microlenses. apparatus. 7. The image display device according to claim 1, wherein at least one of the first and second microlens arrays has a dense arrangement of microlenses. Display device. 8. The image display device according to claim 1, further comprising a spacer for maintaining and / or adjusting a gap and / or a position between the first and second microlens arrays. Characteristic image display device. 9. An image projection device having the image display device according to any one of claims 1 to 8 and a light source and a projection lens.